Protein profile and malt activity during sorghum germination

BACKGROUND: The effect of germination time on major sorghum macromolecules was followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy. Sorghum flour was also incubated with sorghum malt to evaluate amylase and protease activities.RESULTS: The SDS-PAGE results showed that levels of high-molecular-weight aggregates, β monomer and γ and α monomers increased by 120.5, 20.3 and 12.7% respectively during the first few days of germination. This behaviour shows the enhancement of prolamin extractability and concentration in sorghum as a result of starch degradation. After the third day, proteins suffered degradation by intrinsic proteases. FTIR spectroscopy showed a gradual decrease in lipid and protein levels and starch structural changes during the germination period. These modifications are due to intrinsic lipases, proteases and amylases. Sorghum flour was incubated with different malt samples resulting from 0-7 days of germination. It was found that a 5 day malt led to a sixfold increase in carbohydrate digestibility and a fourfold increase in free amino acid content.CONCLUSION: A 5 day sorghum malt is the best inoculum for porridge preparation, representing an inexpensive, effortless and culturally acceptable way to prepare weaning foods at domestic and industrial levels.